Negative electrode active material and negative electrode

Abstract

A negative electrode active material including negative electrode active material particles, wherein the negative electrode active material particles contain silicon oxide particles coated with a carbon layer, at least a part of the silicon oxide particles contains at least one selected from the group consisting of Li 2 SiO 3 , Li 4 SiO 4 , and Li 6 Si 2 O 7 , and a part of at least an outermost layer of the negative electrode active material particles is coated with a layer of a plasticizer. This can provide: a negative electrode active material that can increase stability in slurry formation while achieving sufficient battery characteristics; and a negative electrode including such a negative electrode active material.

1 . A negative electrode active material, comprising negative electrode active material particles, wherein
 the negative electrode active material particles contain silicon oxide particles coated with a carbon layer,   at least a part of the silicon oxide particles contains at least one selected from the group consisting of Li 2 SiO 3 , Li 4 SiO 4 , and Li 6 Si 2 O 7 , and   a part of at least an outermost layer of the negative electrode active material particles is coated with a layer of a plasticizer.   
     
     
         2 . The negative electrode active material according to  claim 1 ,
 wherein the layer of the plasticizer has a thickness of 0.1 nm or more and 10 nm or less.   
     
     
         3 . The negative electrode active material according to  claim 1 , wherein a part of the carbon layer contains a nitrogen atom. 
     
     
         4 . The negative electrode active material according to  claim 3 , wherein the carbon layer is formed with a hydrocarbon material derived from petroleum asphalt as a starting material, and a part thereof contains the nitrogen atom. 
     
     
         5 . The negative electrode active material according to  claim 1 , wherein the plasticizer contains at least one selected from the group consisting of a phthalate ester plasticizer, an adipate ester plasticizer, a phosphate ester plasticizer, and a sulfonamide plasticizer. 
     
     
         6 . The negative electrode active material according to  claim 5 , wherein the plasticizer contains at least one selected from the group consisting of dioctyl phthalate, dibutoxyethyl phthalate, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis(2-butoxyethyl) adipate, triphenyl phosphate, a phthalate-based polyester, an adipate-based polyester, an epoxidated vegetable oil, p-toluenesulfonamide, N-ethyl-o-toluenesulfonamide, N-ethyl-p-toluenesulfonamide, o-toluenesulfonamide, N-n-butylbenzenesulfonamide, and N-cyclohexyl-p-toluenesulfonamide. 
     
     
         7 . The negative electrode active material according to  claim 1 , wherein the layer of the plasticizer further comprises a solid electrolyte. 
     
     
         8 . The negative electrode active material according to  claim 7 , wherein the solid electrolyte contains lithium phosphate and/or aluminum oxide. 
     
     
         9 . The negative electrode active material according to  claim 1 , wherein the negative electrode active material particles before charge-and-discharge have a peak derived from a Si (111) crystal face obtained by X-ray diffraction using Cu-Kα radiation, a crystallite size corresponding to the crystal face is 5.0 nm or less, and a ratio A/B of an intensity A of the peak derived from the Si (111) face relative to an intensity B of a peak derived from a Li 2 SiO 3  (111) crystal face satisfies the following formula (1), 
       
         
           
             
               
                 
                   
                     0.4 
                     ≤ 
                     
                       A 
                       / 
                       B 
                     
                     ≤ 
                     
                       1. 
                       . 
                     
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
       
     
     
         10 . The negative electrode active material according to  claim 1 , wherein the negative electrode active material particles have a median diameter of 4.5 μm or more and 15 μm or less. 
     
     
         11 . A negative electrode, comprising the negative electrode active material according to  claim 1 .